JP2000162583A - Liquid crystal display device and reflection type liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device uniformly applying a voltage to a liquid crystal even while providing a light diffusion layer diffusing a beam, preventing a display defect such as the occurrence of display irregularity and visible from a wide range view angle. SOLUTION: By providing a TFT substrate 10 provided with a TFT and a reflection display electrode 19 connected to the TFT and its protection layer 33 on the light diffusion layer 34 mixed with bead particles 37, the occurrence of a projecting part to a counter electrode 35 and an oriented film 36 due to the projected part of the bead particle 37 is prevented, and a flat surface is obtained. Thus, the voltage is applied uniformly to the liquid crystal 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device having a light diffusion layer and a reflection type liquid crystal display device.

[0002]

2. Description of the Related Art Heretofore, there has been proposed a so-called reflection type liquid crystal display device for displaying a display by reflecting light incident from an observation direction.

FIG. 3 is a sectional view of a reflection type liquid crystal display device.

As shown in FIG. 1, in a reflection type liquid crystal display device, a thin film transistor (hereinafter, referred to as "TFT") as a switching element is formed on an insulating substrate 10 made of quartz glass, non-alkali glass or the like. I do. First, a gate electrode 11 made of a refractory metal such as chromium (Cr) and molybdenum (Mo), a gate insulating film 12, and an active layer 13 made of a polycrystalline silicon film are sequentially formed on an insulating substrate (TFT substrate) 10. Form.

The active layer 13 has a channel 13c above the gate electrode 11, and a source 13s and a drain 1 formed on both sides of the channel 13c by ion implantation using the stopper insulating film 14 on the channel 13c as a mask.
3d is provided.

Then, an SiO ₂ film, a SiN film, and the like are formed on the entire surface of the gate insulating film 12, the active layer 13, and the stopper insulating film 14.
An interlayer insulating film 15 is formed by laminating a film and an SiO ₂ film in this order, and a contact hole provided corresponding to the drain 13 d is filled with a metal such as aluminum (Al) to form a drain electrode 16. Further, a flattening insulating film 17 made of, for example, an organic resin and flattening the surface is formed on the entire surface. Then, a contact hole is formed at a position corresponding to the source 13 s of the planarization insulating film 17, and a reflection electrode which is made of aluminum (Al) contacted with the source 13 s via the contact hole and also serves as the source electrode 18. The display electrode 19 is formed on the flattening insulating film 17.
Then, an alignment film 20 made of an organic resin such as polyimide for aligning the liquid crystal 21 is formed on the reflective display electrode 19.

A counter electrode substrate 30, which is an insulating substrate made of quartz glass, non-alkali glass, or the like, which faces the TFT substrate 10, has red (R), green (G), and blue on the TFT substrate 10 side. (B) A color filter 31 including a black matrix 32 having each color and a light shielding function, a protective film 33 made of a resin formed thereon, a light diffusion layer 34 formed on the entire surface thereof, a counter electrode 35, and an alignment film. 36. Further, a retardation plate 44 and a polarizing plate 45 are disposed on the surface of the insulating substrate 30 opposite to the side on which the alignment film 36 and the like are formed. Then, the counter electrode substrate 30 and T
The periphery of the FT substrate 10 is adhered by a seal adhesive (not shown), and a void formed thereby is filled with a twisted nematic (TN) liquid crystal 21.

The natural light 100 incident from the outside is incident from the polarizing plate 45 on the observer 101 side as shown by the dashed arrow, and the retardation plate 44, the counter electrode substrate 30, the color filter 31, the protective film 33, the light Diffusion layer 34, counter electrode 35, alignment film 36, TN liquid crystal 21, alignment film 2 on TFT substrate 10
0, is reflected by the reflective display electrode 19, and then passes through each layer in the direction opposite to the incident direction, so that the counter electrode substrate 30
The light exits from the upper polarizing plate 45 and enters the eyes 101 of the observer.

[0009]

FIG. 4 shows a partially enlarged view of a part of the reflection type liquid crystal display device of FIG.

As shown in FIG. 1, the light diffusion layer 34 is formed on a protective film 33 for protecting the color filter 31 on the counter electrode substrate 30.

The light diffusing layer 34 is made of a transparent insulating film, for example, an acrylic resin as a base material, and mixed therein with bead particles 37 having a different refractive index from that of the transparent acrylic resin as the base material. In order to further improve the diffusion by the light diffusion layer 34, it is necessary to increase the mixing amount of the bead particles 37.

However, if the mixing amount of the bead particles 37 is increased, when the light diffusion layer 34 is coated on the protective film 33 by a spinner or the like, the acrylic resin protrudes due to the bead particles 37 and the projection on the surface of the light diffusion layer 34. 38 will occur.

Then, ITO (In) is formed on the light diffusion layer 34.
counter electrode 35 made of a transparent conductive film such as dium Tin Oxide)
Is formed, the projections 38 on the surface of the light diffusion layer 34 cause irregularities on the counter electrode 35, and the surface of the counter electrode 35 is not flat.

Further, the alignment film 3 provided on the counter electrode 35
6, a protruding portion occurs, and a flat alignment film surface cannot be obtained.

As a result, since the voltage applied to the liquid crystal 21 is not uniformly applied, the alignment of the liquid crystal 21 varies, and a uniform display cannot be obtained.

Accordingly, the present invention has been made in view of the above-mentioned conventional disadvantages. By providing a light diffusing layer, it is possible to visually recognize a display from a wide range of viewing angles and to uniformly display the liquid crystal. It is an object of the present invention to provide a liquid crystal display device capable of supplying an appropriate voltage and obtaining a uniform display.

[0017]

According to the liquid crystal display device of the present invention, a liquid crystal is sandwiched between first and second substrates arranged opposite to each other, and the first substrate has a switching element, And a display electrode connected to the switching element; a light diffusion layer in which bead particles are mixed in a base made of an insulator on the side of the second substrate facing the first substrate; A protective film for protecting the light diffusion layer is sequentially provided.

Further, the protective film of the above-mentioned liquid crystal display device is made of a material capable of absorbing the projections of the light diffusion layer caused by the bead particles.

Further, the refractive index of the substrate of the light diffusion layer of the liquid crystal display device is equal to the refractive index of the protective film.

Further, in the reflection type liquid crystal display device of the present invention, a liquid crystal is sandwiched between first and second substrates arranged opposite to each other, and a switching element is provided on the first substrate.
And a reflective display electrode made of a reflective material connected to the switching element, wherein the second substrate has a light diffusion in which bead particles are mixed in a base made of an insulator on a surface facing the first substrate. And a protective film for protecting the light diffusion layer in this order.

The protective film of the above-mentioned reflection type liquid crystal display device is made of a material capable of absorbing the projections of the light diffusion layer caused by the bead particles.

Further, the refractive index of the substrate of the light diffusion layer of the reflection type liquid crystal display device is equal to the refractive index of the protective film.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The reflection type liquid crystal display of the present invention will be described below.

FIG. 1 is a sectional view of a reflection type liquid crystal display device of the present invention.

As shown in FIG. 1, a TFT as a switching element is formed on an insulating substrate 10 made of quartz glass, non-alkali glass or the like.

In the case of this embodiment, one of the insulating substrates 1
Gate electrode 1 made of a high melting point metal such as Cr, Mo, etc.
1 to the formation of the planarization insulating film 17 are the same as those of the above-described structure, and a description thereof will be omitted.

On the flattening insulating film 17, A is connected to the source 13s of the active layer 13 made of a polycrystalline silicon film.
1. A reflective display electrode 19 made of a conductive reflective material such as silver (Ag) is formed. On the display electrode 19, an alignment film 20 made of polyimide or the like for aligning the liquid crystal is formed.

On the other side of the counter electrode substrate 30 made of quartz glass, non-alkali glass or the like, a black matrix 32 having colors of R, G, and B and a light shielding function is provided on the side where the liquid crystal 21 is disposed. Color filter 31,
On the color filter 31, an insulating film, for example, a light diffusion layer 34 made of an acrylic resin as a base and mixed with bead particles is formed. Then, a protective film 33 made of an acrylic resin or the like is provided thereon. On the protective film 33, a counter electrode 35 facing each reflective display electrode 19 is provided on the entire surface. Further, an alignment film 36 made of polyimide is formed on the entire surface.

On the side of the counter electrode substrate 30 where no liquid crystal is arranged, that is, on the observer side, a phase difference (λ / 4) plate 44 and a polarizing plate 45 are provided in this order from the counter electrode substrate 30 side.

Further, as the liquid crystal 21, for example, a TN liquid crystal is used.

Natural light 100 incident from the outside is shown in FIG.
As shown by the dotted arrow inside, the polarizing plate 4 on the observer 101 side
5, passes through the phase difference plate 44, the counter electrode substrate 30, and the color filter 31, and reaches the light diffusion layer 34.
Here, the light is diffused, and the diffused light is
3. The light passes through the counter electrode 35, the alignment film 36, the liquid crystal 21, and the alignment film 20 on the TFT substrate 10, and reaches the reflective display electrode 19. The arriving light is reflected by the reflective display electrode 19. The reflected light reaches the light diffusion layer 34 and is diffused, passes through the phase difference plate 44 and the polarizing plate 45, and
1 is observed.

Therefore, at the time of incidence of light and at the time of emission after reflection, light is diffused by the light diffusion layer 34.
The observer 101 can see a uniform and bright display on the entire surface of the liquid crystal display device.

FIG. 2 is a partial sectional view of the reflection type liquid crystal display of FIG.

As shown in the figure, a black matrix 32 is provided on the side where the liquid crystal 21 is disposed on the counter electrode substrate 30.
The light diffusion layer 34 for diffusing light is provided on the color filter 31 having

The light diffusion layer 34 is formed of the color filter 31.
Is formed, an acrylic resin, which is a substrate mixed with bead particles 37 in advance, is coated with a color filter 3 using a spinner.
1 is coated on the entire surface. Its thickness is about 8μm ~ 1
It is about 1 μm. The bead particles 37 are generally spherical and have a diameter of about 2 μm to 5 μm.

Then, a transparent insulating film, for example, an acrylic resin is applied on the entire surface of the light diffusion layer 34 by a spinner to form a protective film 33. After that, the ITO is
Is formed by sputtering, and an alignment film 36 made of a resin such as polyimide is formed thereon to align the liquid crystal 21. At this time, if the refractive index of the base of the light diffusion layer 34 and the refractive index of the protective film 33 are different, light incident from the light diffusion layer 34 side is reflected at the boundary with the protective film, and the observer 101 Therefore, it is preferable that the refractive index of the base of the light diffusion layer 34 and the refractive index of the protective film 33 are equal to each other. In the present embodiment, an acrylic resin having a refractive index of 1.4 to 1.6 is used.

Thus, each layer of the counter electrode substrate 30 provided with the light diffusion layer 34 on the side where the liquid crystal 21 is arranged is completed. Note that a phase difference plate 44 and a polarizing plate 45 are provided on the viewer 101 side of the counter electrode substrate 30.

As described above, by increasing the amount of the bead particles 37 to further improve the diffusion of the light diffusion layer 34 provided on the color filter 31, the light diffusion layer 34 formed by the bead particles 37 is about 200 to 2000 degrees. Even if a projection is generated, by providing the protective film 33 on the light diffusion layer 34, the projection on the alignment film due to the projection is eliminated, and a flat surface can be obtained for the counter electrode and the alignment film. it can.

That is, the light diffusion layer 3 is formed by the bead particles 37.
4 is a material capable of absorbing the height of the projection even if a projection is formed, in other words, a material having a flat surface regardless of the unevenness even when formed on the surface of the uneven shape, for example, Since the protection film 33 made of an acrylic resin is formed on the light diffusion layer 34, the surface of the protection film 33 can be made flat after the formation of the protection film 33. Therefore, the counter electrode 35 and the alignment film 36 formed on the protective film 33 are formed.
Can have a flat surface.

As a result, the voltage applied to the counter electrode 35 is uniformly applied to the liquid crystal 21, so that the alignment of the liquid crystal 21 does not vary, and display defects that cause uneven display can be prevented. Further, since the light diffusion layer 34 can be provided, the display can be viewed uniformly and brightly over the entire surface of the liquid crystal display device.

In the above-described embodiment, the case of the reflection type liquid crystal display device has been described. However, the present invention is not limited to this, and the present invention can be applied to a transmission type liquid crystal display device. A similar effect can be obtained.

Further, in the above-described embodiment, the case where a color filter is used has been described. However, the present invention is not limited to this, and the color filter 31 is not provided in FIGS. Even if the light diffusion layer 34 is provided directly on the substrate 30, the protruding portion is formed by the protection layer 33 provided thereon.
The surface of the protective film can be absorbed and flattened, so that the surfaces of the counter electrode 35 and the alignment film 36 formed thereon can be flattened, so that a voltage is uniformly applied to the liquid crystal and a display without unevenness can be obtained. be able to.

[0043]

According to the present invention, since the voltage of the counter electrode is uniformly applied to the liquid crystal, display defects such as uneven display can be prevented, and the light diffusing layer allows viewing from a wide viewing angle. Is possible.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of a liquid crystal display device of the present invention.

FIG. 2 is a partially enlarged view of the liquid crystal display device of the present invention.

FIG. 3 is a sectional view showing a second embodiment of the liquid crystal display device of the present invention.

FIG. 4 is a sectional view of a conventional reflection type liquid crystal display device.

[Explanation of symbols]

 Reference Signs List 10 TFT substrate 13 Active layer 15 Interlayer insulating film 19 Reflective display electrode 21 Liquid crystal 26 Flattening insulating film 33 Protective film 34 Light diffusion layer 37 Bead particles 44 Phase difference plate 45 Polarizing plate

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G02F 1/1343 G02F 1/1343 1/136 500 1/136 500 H01L 29/786 H01L 29/78 612Z 21 / 336 F-term (reference) 2H042 BA02 BA15 BA20 2H090 HA04 HB07X HB08Y HC05 HD03 HD06 HD14 2H091 FA02Y FA08X FA11X FA14Y FA31Y FB02 FB08 FB11 GA01 GA02 GA06 GA13 GA16 HA07 KA01 LA16 LA19 2H092A05 A04 DD03 GG02 GG13 HL03

Claims (6)

[Claims] 1. A first and a second arrangement arranged opposite to each other.
Liquid crystal is sandwiched between the substrates, the first substrate includes a switching element, and a display electrode connected to the switching element, and the second substrate has a surface facing the first substrate. A liquid crystal display device comprising, on a side, a light diffusion layer in which bead particles are mixed in a base made of an insulator, and a protective film for protecting the light diffusion layer. 2. The liquid crystal display device according to claim 1, wherein the protective film is made of a material capable of absorbing protrusions of the light diffusion layer caused by the bead particles. 3. The liquid crystal display device according to claim 1, wherein the refractive index of the substrate of the light diffusion layer is equal to the refractive index of the protective film. 4. A first and a second, which are arranged opposite to each other.
Liquid crystal is interposed between the substrates, the first substrate includes a switching element, and a reflective display electrode connected to the switching element and made of a reflective material. The second substrate includes the first substrate. A reflection type liquid crystal display device comprising: a light diffusion layer in which bead particles are mixed in a base made of an insulator; and a protective film for protecting the light diffusion layer, in that order on the surface facing the substrate. 5. The reflection type liquid crystal display device according to claim 4, wherein the protective film is made of a material capable of absorbing protrusions of the light diffusion layer caused by the bead particles. 6. The light diffusion layer according to claim 4, wherein a refractive index of a substrate of the light diffusion layer is equal to a refractive index of the protective film.
3. The reflection type liquid crystal display device according to item 1.